Association between obstructive sleep apnea and metabolic syndrome: a meta-analysis

Purpose: Evidence suggests that obstructive sleep apnea (OSA) is related to metabolic syndrome; however, the relationship among metabolic syndrome parameters (blood pressure, fasting blood glucose (FBG), high density lipoprotein (HDL) and low density lipoprotein (LDL)) and OSA is unclear. Methods: PRISMA guidelines were followed for this study. Medline, Cochrane, EMBASE and Google Scholar databases were searched until December 23, 2015, using following terms: obstructive sleep apnea, sleep apnea, OSA and metabolic syndrome. Results: Ten studies were included in the analysis which included 2053 patients. Patients with OSA had higher systolic blood pressure (SBP) (pooled standard mean difference (SMD) = 0.56, 95% CI, 0.40 to 0.71, P<0.001), lower levels of HDL (pooled SMD = -0.27, 95% CI, -0.38 to -0.16, P<0.001), and higher levels LDL (pooled SMD = 0.26, 95% CI, 0.07 to 0.45, P=0.007) than patients without OSA. OSA was also found to be associated with increased triglyceride levels (pooled SMD = 0.26, 95% CI, 0.07 to 0.45, P=0.007) and higher FBG (pooled SMD = 0.35, 95% CI, 0.18 to 0.53, P<0.001). Conclusion: This meta-analysis found that OSA was associated with abnormal levels of multiple parameters that are markers for metabolic syndrome, and suggests that OSA broadly affects this disease. Understanding the relationships between OSA and metabolic syndrome may allow the early identification of OSA patients who may develop diseases related to metabolic syndrome such as type 2 diabetes and cardiovascular disease.